Wideband balanced duplexer

ABSTRACT

Embodiments disclosed herein relate to isolating a receiver circuit of an electronic device from a transmission signal and leakage of the transmission signal. To do so, an isolation circuit is disposed between the receiver circuit and a transmission circuit. The isolation circuit may include multiple variable impedance devices and one or more antennas. The impedances of the variable impedance devices may be balanced such that a signal at a particular frequency or within a particular frequency band can pass through or is blocked by the isolation circuit. The isolation circuit may include one or more double balanced duplexers to achieve the improved isolation. The isolation circuit may also increase bandwidth available for wireless communications of the electronic device.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to and benefit of U.S. patentapplication Ser. No. 17/116,360, filed Dec. 9, 2020, and entitled“WIDEBAND BALANCED DUPLEXER,” which is incorporated herein by referencein its entirety for all purposes.

BACKGROUND

The present disclosure relates generally to wireless communication, andmore specifically to isolation of high bandwidth wireless signalsbetween transmitters and receivers in wireless communication devices.

In an electronic device, a transmitter and a receiver may each becoupled to an antenna to enable the electronic device to both transmitand receive wireless signals. The electronic device may include anelectrical balanced duplexer (EBD) that isolates the transmitter fromreceived signals of a first frequency range, and isolates the receiverfrom transmission signals of a second frequency range (e.g., thusimplementing frequency division duplex (FDD) operations). In thismanner, interference between the transmission and received signals maybe reduced when communicating using the electronic device. However,these communications may be negatively impacted by insertion lossresulting from components of the EBD providing less than ideal isolationof the transmission and/or received signals. Moreover, a bandwidth of anEBD or conventional double balanced duplexer may not be sufficient tosupport high bandwidth (e.g., greater than 10 MHz) operations.

SUMMARY

A summary of certain embodiments disclosed herein is set forth below. Itshould be understood that these aspects are presented merely to providethe reader with a brief summary of these certain embodiments and thatthese aspects are not intended to limit the scope of this disclosure.Indeed, this disclosure may encompass a variety of aspects that may notbe set forth below.

An aspect of the disclosure provides an electronic device that may haveone or more antennas. The electronic device may have transmit circuitrythat sends a transmission signal to the one or more antennas and receivecircuitry that receives a reception signal from the one or moreantennas. The electronic device may have isolation circuitry including afirst balun coupled to the one or more antennas and the transmitcircuitry may isolate the transmit circuitry from the reception signal.The isolation circuitry may have a second balun coupled to the one ormore antennas and the transmit circuitry in parallel with the firstbalun. The second balun may prevent a leakage signal from the transmitcircuitry from entering the receive circuitry.

Another aspect of the disclosure provides radio frequency transceivercircuitry that may have transmit circuitry communicatively coupled toone or more antennas. The radio frequency transceiver circuitry may havereceive circuitry communicatively coupled to the one or more antennas.The radio frequency transceiver circuitry may have a first duplexercoupled to and disposed between the receive circuitry and the one ormore antennas. The first duplexer may have a first balun transformer anda first set of variable impedance devices coupled to the first baluntransformer. The radio frequency transceiver circuitry may have a secondduplexer coupled to and disposed between the receive circuitry and theone or more antennas. The second duplexer may have a second baluntransformer and a second set of variable impedance devices coupled tothe second balun transformer.

Another aspect of the disclosure provides a user equipment including oneor more antennas and a power amplifier. The user equipment may haveisolation circuitry having a first transformer coupled to and disposedbetween the power amplifier and the one or more antennas. The isolationcircuitry may have a first variable impedance device coupled to thefirst transformer, and a second variable impedance device coupled to thefirst transformer. The isolation circuitry may have a second transformercoupled to and disposed between the power amplifier and the one or moreantennas. The second transformer may be disposed in parallel with thefirst transformer. The isolation circuitry may have a third variableimpedance device coupled to the second transformer, and a fourthvariable impedance device coupled to the second transformer.

Various refinements of the features noted above may exist in relation tovarious aspects of the present disclosure. Further features may also beincorporated in these various aspects as well. These refinements andadditional features may exist individually or in any combination. Forinstance, various features discussed below in relation to one or more ofthe illustrated embodiments may be incorporated into any of theabove-described aspects of the present disclosure alone or in anycombination. The brief summary presented above is intended only tofamiliarize the reader with certain aspects and contexts of embodimentsof the present disclosure without limitation to the claimed subjectmatter.

BRIEF DESCRIPTION OF THE DRAWINGS

Various aspects of this disclosure may be better understood upon readingthe following detailed description and upon reference to the drawingsdescribed below in which like numerals refer to like parts.

FIG. 1 is a block diagram of an electronic device, according to anembodiment of the present disclosure.

FIG. 2 is a functional block diagram of the electronic device of FIG. 1that may implement the components shown in FIG. 1 and/or the circuitryand/or components described in the following figures, according toembodiments of the present disclosure.

FIG. 3 is a block diagram of example transceiver circuitry of theelectronic device of FIG. 1, according to an embodiment of the presentdisclosure.

FIG. 4A is a schematic diagram of a receiver circuit of the exampletransceiver circuitry of FIG. 3, according to an embodiment of thepresent disclosure.

FIG. 4B is a schematic diagram of a transmitter circuit of the exampletransceiver circuitry of FIG. 3, according to an embodiment of thepresent disclosure.

FIG. 5 is a schematic diagram of the example transceiver circuitry ofFIG. 3 having baluns to isolate the transmitter/receiver circuits fromreceived/transmission signals and baluns to reduce insertion loss,according to an embodiment of the present disclosure.

FIG. 6 is a schematic diagram of an example duplexer of the transceivercircuitry of FIG. 3 having additional variable impedance devices toenhance isolation, according to an embodiment of the present disclosure.

FIG. 7 is a schematic diagram of an example double balanced duplexerimplemented with the duplexer of FIG. 6, according to an embodiment ofthe present disclosure.

FIG. 8 is a schematic diagram of an example quadplexer module of thetransceiver circuitry of the electronic device of FIG. 1, according toan embodiment of the present disclosure.

FIG. 9 is a schematic diagram illustrating example components of theexample quadplexer module of FIG. 8, according to an embodiment of thepresent disclosure.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

One or more specific embodiments will be described below. In an effortto provide a concise description of these embodiments, not all featuresof an actual implementation are described in the specification. Itshould be appreciated that in the development of any such actualimplementation, as in any engineering or design project, numerousimplementation-specific decisions must be made to achieve thedevelopers' specific goals, such as compliance with system-related andbusiness-related constraints, which may vary from one implementation toanother. Moreover, it should be appreciated that such a developmenteffort might be complex and time consuming, but would nevertheless be aroutine undertaking of design, fabrication, and manufacture for those ofordinary skill having the benefit of this disclosure.

When introducing elements of various embodiments of the presentdisclosure, the articles “a,” “an,” and “the” are intended to mean thatthere are one or more of the elements. The terms “comprising,”“including,” and “having” are intended to be inclusive and mean thatthere may be additional elements other than the listed elements.Additionally, it should be understood that references to “oneembodiment” or “an embodiment” of the present disclosure are notintended to be interpreted as excluding the existence of additionalembodiments that also incorporate the recited features. Furthermore, theparticular features, structures, or characteristics may be combined inany suitable manner in one or more embodiments. Use of the term“approximately,” “near,” “about”, and/or “substantially” should beunderstood to mean including close to a target (e.g., design, value,amount), such as within a margin of any suitable or contemplatable error(e.g., within 0.1% of a target, within 1% of a target, within 5% of atarget, within 10% of a target, within 25% of a target, and so on).

This disclosure is directed to isolation of wireless signals betweentransmitters and receivers in wireless communication devices using adouble balanced duplexer (DBD). When using a DBD in an electronic deviceto isolate a transmitter from received signals and isolate a receiverfrom transmission signals, variable impedance devices (e.g., impedancegradients, impedance tuners) may be used to place baluns (e.g.,transformers) of the DBD in balanced and unbalanced states to block andenable pass-through of signals. For example, an impedance gradientcoupled to a balun may function as a filter with a high impedance in apass band and a low impedance in the block (e.g., stop) band.Conversely, an impedance tuner coupled to the balun may function as afilter with a low impedance in the pass band and a high impedance in theblock band. As a result, in the pass band, the balun is unbalanced, andsignals having frequencies in the pass band pass through the balun. Inthe block band, the balun is balanced, and signals are destructivelycombined at the balun. However, the bandwidth of the pass band of theDBD may be limited (e.g., to about 10 megahertz (MHz)). Further,insertion loss (e.g., lost power) caused by non-ideal components of theDBD operating in real-world conditions may degrade communicationcapabilities of the DBD.

Embodiments herein provide various apparatuses and techniques to reduceinsertion loss while increasing the bandwidth of the DBD and maintainingor improving isolation of the transmitter and receiver of an electronicdevice. To do so, the embodiments disclosed herein include isolationcircuitry that may have a first balun coupled between a transmitter andan antenna that isolates the transmitter from received signals receivedby the antenna, and enables transmission signals sent from thetransmitter to pass through to the antenna. The isolation circuitry mayalso have a second balun coupled between the transmitter and the antennathat substantially prevents, reduces, or mitigates a leakage signal fromthe transmitter to a receiver. The isolation circuitry may furtherinclude a third balun coupled between the antenna and the receiver thatisolates the receiver from the transmission signals, and enables thereceived signals to pass from the antenna to the receiver. The isolationcircuitry may additionally include a fourth balun that substantiallyprevents, reduces, or mitigates a leakage signal from the antenna to thetransmitter.

Each balun may include a set of coils, such as four coils. In someembodiments, one pair of the coils (e.g., on a transmitter side of thebalun, on a receiver side of the balun, on an antenna side of the balun)may be coupled to variable impedance devices that are tunable to placethe respective balun in a balanced or unbalanced state. In suchembodiments, the other pair of coils may not be coupled to such variableimpedance devices. However, in some embodiments, each pair of coils ofthe balun may be coupled to variable impedance devices, such that eachpair may operate in the balanced state to enhance isolation of thereceiver from transmission signals and/or enhance isolation of thetransmitter from received signals.

FIG. 1 is a block diagram of an electronic device 10, according to anembodiment of the present disclosure. The electronic device 10 mayinclude, among other things, one or more processors 12 (collectivelyreferred to herein as a single processor for convenience, which may beimplemented in any suitable form of processing circuitry), memory 14,nonvolatile storage 16, a display 18, input structures 22, aninput/output (I/O) interface 24, a network interface 26, and a powersource 29. The various functional blocks shown in FIG. 1 may includehardware elements (including circuitry), software elements (includingcomputer code stored on a computer-readable medium) or a combination ofboth hardware and software elements. The processor 12, memory 14, thenonvolatile storage 16, the display 18, the input structures 22, theinput/output (I/O) interface 24, the network interface 26, and/or thepower source 29 may each be communicatively coupled directly orindirectly (e.g., through or via another component, a communication bus,a network) to one another to transmit and/or receive data between oneanother. It should be noted that FIG. 1 is merely one example of aparticular implementation and is intended to illustrate the types ofcomponents that may be present in electronic device 10.

By way of example, the electronic device 10 may represent a blockdiagram of any suitable computing device, including a desktop computer,a notebook computer, a portable electronic or handheld electronic device(e.g., a wireless electronic device or smartphone), a tablet, a wearableelectronic device, and other similar devices. It should be noted thatthe processor 12 and other related items in FIG. 1 may be generallyreferred to herein as “data processing circuitry.” Such data processingcircuitry may be embodied wholly or in part as software, software,hardware, or any combination thereof. Furthermore, the processor 12 andother related items in FIG. 1 may be a single contained processingmodule or may be incorporated wholly or partially within any of theother elements within the electronic device 10. The processor 12 may beimplemented with any combination of general-purpose microprocessors,microcontrollers, digital signal processors (DSPs), field programmablegate array (FPGAs), programmable logic devices (PLDs), controllers,state machines, gated logic, discrete hardware components, dedicatedhardware finite state machines, or any other suitable entities that mayperform calculations or other manipulations of information. Theprocessors 12 may perform the various functions described herein andbelow.

In the electronic device 10 of FIG. 1, the processor 12 may be operablycoupled with a memory 14 and a nonvolatile storage 16 to perform variousalgorithms. Such programs or instructions executed by the processor 12may be stored in any suitable article of manufacture that includes oneor more tangible, computer-readable media. The tangible,computer-readable media may include the memory 14 and/or the nonvolatilestorage 16, individually or collectively, to store the instructions orroutines. The memory 14 and the nonvolatile storage 16 may include anysuitable articles of manufacture for storing data and executableinstructions, such as random-access memory, read-only memory, rewritableflash memory, hard drives, and optical discs. In addition, programs(e.g., an operating system) encoded on such a computer program productmay also include instructions that may be executed by the processor 12to enable the electronic device 10 to provide various functionalities.

In certain embodiments, the display 18 may facilitate users to viewimages generated on the electronic device 10. In some embodiments, thedisplay 18 may include a touch screen, which may facilitate userinteraction with a user interface of the electronic device 10.Furthermore, it should be appreciated that, in some embodiments, thedisplay 18 may include one or more liquid crystal displays (LCDs),light-emitting diode (LED) displays, organic light-emitting diode (OLED)displays, active-matrix organic light-emitting diode (AMOLED) displays,or some combination of these and/or other display technologies.

The input structures 22 of the electronic device 10 may enable a user tointeract with the electronic device 10 (e.g., pressing a button toincrease or decrease a volume level). The I/O interface 24 may enableelectronic device 10 to interface with various other electronic devices,as may the network interface 26. The network interface 26 may include,for example, one or more interfaces for a personal area network (PAN),such as a BLUETOOTH® network, for a local area network (LAN) or wirelesslocal area network (WLAN), such as a network employing one of the IEEE802.11x family of protocols (e.g., WI-FI®), and/or for a wide areanetwork (WAN), such as any standards related to the Third GenerationPartnership Project (3GPP), including, for example, a 3^(rd) generation(3G) cellular network, universal mobile telecommunication system (UMTS),4^(th) generation (4G) cellular network, long term evolution (LTE®)cellular network, long term evolution license assisted access (LTE-LAA)cellular network, 5^(th) generation (5G) cellular network, and/or NewRadio (NR) cellular network. In particular, the network interface 26 mayinclude, for example, one or more interfaces for using a Release-15cellular communication standard of the 5G specifications that includethe millimeter wave (mmWave) frequency range (e.g., 24.25-300 gigahertz(GHz)). The network interface 26 of the electronic device 10 may allowcommunication over the aforementioned networks (e.g., 5G, Wi-Fi,LTE-LAA, and so forth).

The network interface 26 may also include one or more interfaces for,for example, broadband fixed wireless access networks (e.g., WIMAX®),mobile broadband Wireless networks (mobile WIMAX®), asynchronous digitalsubscriber lines (e.g., ADSL, VDSL), digital videobroadcasting-terrestrial (DVB-T®) network and its extension DVB Handheld(DVB-H®) network, ultra-wideband (UWB) network, alternating current (AC)power lines, and so forth.

As illustrated, the network interface 26 may include a transceiver 30.In some embodiments, all or portions of the transceiver 30 may bedisposed within the processor 12. The transceiver 30 may supporttransmission and receipt of various wireless signals via one or moreantennas (not shown in FIG. 1). In some cases, an impedance of the oneor more antennas may disturb the duplex function and degrade isolationbetween the transmit path and the receive path. To prevent suchdisruption by the one or more antennas, a variable impedance device,such as an impedance tuner, may be used to substantially match animpedance of the antenna.

In some embodiments, the transceiver 30 may include a duplexer (notshown in FIG. 1). A duplexer enables bidirectional communication over asingle path while separating signals traveling in each direction fromone another. For example, the duplexer may enable frequency divisionduplexing (FDD), such that the duplexer may isolate a transmitter of theelectronic device 10 from a received signal of a first frequency bandwhile isolating a receiver of the electronic device 10 from atransmission signal of a second frequency band (e.g., isolate thetransmitter from the receiver, and vice versa). In some embodiments, theduplexer may include multiple variable impedance devices that isolatethe transmitter from a received signal and/or isolates the receiver froma transmission signal. The duplexer may include an electrical balancedduplexer, a double balanced duplexer, or any other suitable form ofduplexer.

The power source 29 of the electronic device 10 may include any suitablesource of power, such as a rechargeable lithium polymer (Li-poly)battery and/or an alternating current (AC) power converter. In certainembodiments, the electronic device 10 may take the form of a computer, aportable electronic device, a wearable electronic device, or other typeof electronic device.

FIG. 2 is a functional block diagram of the electronic device 10 thatmay implement the components shown in FIG. 1 and/or the circuitry and/orcomponents described in the following figures, according to embodimentsof the present disclosure. As illustrated, the processor 12, the memory14, the transceiver 30, the transmitter 52, the receiver 54, and/or theantennas 55 (illustrated as 55 a-55 n) may be communicatively coupleddirectly or indirectly (e.g., through or via another component, acommunication bus, a network) to one another to transmit and/or receivedata between one another.

The electronic device 10 may include the transmitter 52 and/or thereceiver 54 that respectively enable transmission and reception of databetween the electronic device 10 and a remote location via, for example,a network or direction connection associated with the electronic device10 and an external transceiver (e.g., in the form of a cell, eNB(E-UTRAN Node B or Evolved Node B), base stations, and the like. Asillustrated, the transmitter 52 and the receiver 54 may be combined intothe transceiver 30. The electronic device 10 may also have one or moreantennas 55 a through 55 n electrically coupled to the transceiver 30.The antennas 55 a-55 n may be configured in an omnidirectional ordirectional configuration, in a single-beam, dual-beam, or multi-beamarrangement, and so on. Each antenna 55 may be associated with a one ormore beams and various configurations. In some embodiments, each beam,when implement as multi-beam antennas, nay have its own transceiver 30.The electronic device 10 may include (not shown) multiple transmitters,multiple receivers, multiple transceivers, and/or multiple antennas asneeded for various communication standards.

The transmitter 52 may be configured to wirelessly transmit packetshaving different packet types or functions. For example, the transmitter52 may be configured to transmit packets of different types generated bythe processor 12. The receiver 54 may be configured to wirelesslyreceive packets having different packet types. In some examples, thereceiver 54 may be configured to detect a type of a packet used and toprocess the packet accordingly. In some embodiments, the transmitter 52and the receiver 54 may be configured to transmit and receiveinformation via other wired or wireline systems or means.

As illustrated, the various components of the electronic device 10 maybe coupled together by a bus system 56. The bus system 56 may include adata bus, for example, as well as a power bus, a control signal bus, anda status signal bus, in addition to the data bus. The components of theelectronic device 10 may be coupled together or accept or provide inputsto each other using some other mechanism.

As mentioned above, the transceiver 30 of the electronic device 10 mayinclude a transmitter and a receiver that are coupled to at least oneantenna to enable the electronic device 10 to transmit and receivewireless signals. The electronic device 10 may include isolationcircuity having one or more baluns coupled to multiple variableimpedance devices that isolate the transmitter from received signals,and the receiver from transmission signals, thus reducing interferencewhen communicating. In particular, a pair of variable impedance devicescoupled to a balun may be tuned to a balanced state to block signals ofa certain frequency range (e.g., a block band) from passing through, andmay be tuned to an unbalanced state to enable signals of anotherfrequency range (e.g., a pass band) to pass through. However, thetransmission path for transmission signals sent from the transmitter maybranch from the antenna toward the receiver. Accordingly, the branchedtransmission signal that travels in the direction of the receiver may bea leakage signal that can interfere with signals received by theantenna. Further, in some cases, a portion of the signals received bythe antennas may branch toward the transmitter. The branched receivedsignal that travels in the direction of the transmitter may be anadditional or alternative leakage signal that can interfere with signalsto be transmitted via the antenna.

Embodiments herein provide various apparatuses and techniques to reduceor substantially prevent such interference by maintaining isolation ofthe transmitter and receiver of the electronic device 10. To do so, theembodiments disclosed herein include isolation circuitry that may have afirst balun coupled between the transmitter and the antenna thatisolates the transmitter from received signals received by the antenna,and enables transmission signals sent from the transmitter to passthrough to the antenna. The isolation circuitry may also have a secondbalun coupled between the transmitter and the antenna that substantiallyprevents, reduces, or mitigates a leakage signal from the transmitter toa receiver. The isolation circuitry may further include a third baluncoupled between the antenna and the receiver that isolates the receiverfrom the transmission signals, and enables the received signals to passfrom the antenna to the receiver. The isolation circuitry mayadditionally include a fourth balun that substantially prevents,reduces, or mitigates a leakage signal from the antenna to thetransmitter.

Each balun may include a set of coils, such as four coils. In someembodiments, one pair of the coils (e.g., on a transmitter side of thebalun, on a receiver side of the balun, on an antenna side of the balun)may be coupled to variable impedance devices that are tunable to placethe respective balun in a balanced or unbalanced state. In suchembodiments, the other pair of coils may not be coupled to such variableimpedance devices. However, in some embodiments, each pair of coils ofthe balun may be coupled to variable impedance devices, such that eachpair may operate in the balanced state to enhance isolation of thereceiver from transmission signals and/or enhance isolation of thetransmitter from received signals.

FIG. 3 is a block diagram of example transceiver circuitry 50 of theelectronic device 10, according to an embodiment of the presentdisclosure. In some embodiments, the example transceiver circuitry 50may be disposed in the transceiver 30 discussed with respect to FIG. 1.In other embodiments, the transceiver circuitry 50 may be disposed inthe network interface 26 and coupled to the transceiver 30.

As illustrated, the transceiver circuitry 50 includes an isolationcircuit 58 disposed between a transmit (TX) circuit 52 and a receive(RX) circuit 54. The isolation circuit 58 is communicatively coupled tothe TX circuit 52 and the RX circuit 54. In some embodiments, theisolation circuit 58 is coupled to one or more antennas 55. In somealternative embodiments, the one or more antennas 55 may be disposedwithin the isolation circuit 58. The isolation circuit 58 enablessignals (e.g., transmission signals) of a first frequency range from theTX circuit 52 to pass through to the one or more antennas 55 and blocksthe signals of the first frequency range from passing through to the RXcircuit 54. The isolation circuit 58 also enables signals (e.g.,received signals) of a second frequency range received via the one ormore antennas 55 to pass through to the RX circuit 54 and blocks thereceived signals of the second frequency range from passing through tothe TX circuit 52. Each frequency range may be of any suitable bandwidthgreater than about 10 MHz, such as between 1 and 100 gigahertz (GHz)(e.g., 10 megahertz (MHz)), and include any suitable frequencies. Forexample, the first frequency range (e.g., the TX frequency range) may bebetween 880 and 890 MHz, and the second frequency range (e.g., the RXfrequency range) may be between 925 and 936 MHz.

In some embodiments, the isolation circuit 58 isolates the RX circuit 54from a transmission (TX) signal generated by the TX circuit 52. Forexample, when transmitting a TX signal, some of the TX signal (e.g., aTX leakage signal) may propagate toward the RX circuit 54. If afrequency of the TX leakage signal is within the RX frequency range(e.g., is a frequency supported by the RX circuit 54), the TX leakagesignal may interfere with an RX signal and/or the RX circuit 54. Toprevent such interference, the isolation circuit 58 may isolate the RXcircuit 54 from the TX leakage signal.

In additional or alternative embodiments, the isolation circuit 58isolates the TX circuit 52 from a received (RX) signal received via theone or more antennas 55. For example, when receiving an RX signal fromthe one or more antennas 55, some of the RX signal (e.g., an RX leakagesignal) may propagate toward the TX circuit 52. If a frequency of the RXleakage signal is within the TX frequency range (e.g., is a frequencysupported by the TX circuit 52), the RX leakage signal may interferewith the TX signal and/or the TX circuit 52. To prevent suchinterference, the isolation circuit 58 may isolate the TX circuit 52from the RX leakage signal.

FIG. 4A is a schematic diagram of the receive circuit (e.g., the RXcircuit) 54, according to an embodiment of the present disclosure. Asillustrated, the RX circuit 54 may include, for example, a low noiseamplifier (LNA) 60, filter circuitry 61, a demodulator 62, and ananalog-to-digital converter (ADC) 63. One or more signals received bythe one or more antennas 55 may be sent to the RX circuit 54 via theisolation circuit 58. In some embodiments, the RX circuit 54 may includecomponents in addition to or alternative to the LNA 60, filter circuitry61, the demodulator 62, and the ADC 63, such as a mixer, a digital downconverter, and the like.

The LNA 60 and filter circuitry 61 may receive the RX signal received bythe one or more antennas 55. The LNA 60 may amplify the RX signal to asuitable level for the rest of the circuitry to process. The filtercircuitry 61 may include one or more types of filters such as bandpassfilter, a low pass filter, or a decimation filter, or any combinationthereof. The filter circuitry 61 may remove undesired noise from the RXsignal, such as cross-channel interference. The filter circuitry 61 mayalso remove additional signals received by the one or more antennas 55which are at frequencies other than the desired signal. The filtered RXsignal is sent to the demodulator 62. The demodulator 62 may remove theRF envelope and extract a demodulated signal from the filtered RX signalfor processing. The ADC 63 receives the demodulated analog signal andconverts the signal to a digital signal so that it can be furtherprocessed by the electronic device 10.

FIG. 4B is a schematic diagram of the transmission circuit (e.g., the TXcircuit) 52, according to an embodiment of the present disclosure. Asillustrated, the TX circuit 52 may include, for example, filtercircuitry 64, a power amplifier (PA) 65, a modulator 66, and adigital-to-analog converter (DAC) 67. In some embodiments, the TXcircuit 52 may include components in addition to or alternative to thefilter circuitry 64, the PA 65, the modulator 66, and the DAC 67 such asa digital up converter, etc.

A digital signal containing information to be transmitted via the one ormore antennas 55 is provided to the DAC 67. The DAC 67 converts thedigital signal to an analog signal. The modulator 66 may combine theconverted analog signal with a carrier signal to generate a radio wave.The PA 65 receives signal the modulated signal from the modulator 66.The PA 65 amplifies the modulated signal to a suitable level to drivetransmission of the signal via the one or more antennas 55. Similar tothe filter circuitry 61, the filter circuitry 64 of the TX circuit 52may remove undesirable noise from the amplified signal to be transmittedvia the one or more antennas 55.

FIG. 5 is a schematic diagram of the transceiver circuitry 50 of FIG. 3having baluns (e.g., 70, 72) to isolate the transmitter/receivercircuits from received/transmission signals and baluns (e.g., 74, 76) toreduce insertion loss, according to an embodiment of the presentdisclosure. As illustrated, the isolation circuitry 58 two baluns 70, 72disposed in parallel between the TX circuit 52 and the one or moreantennas 55, and two baluns 74, 76 disposed in parallel between the RXcircuit 54 and the one or more antennas 55. The baluns 70, 72 arecoupled to the one or more antennas 55 via a first node 94, and the twobaluns 74, 76 are coupled to the one or more antennas 55 via a secondnode 96.

Variable impedance devices 78, 80, 82, 84, 86, 88, 90, 92 are coupled toeach of the baluns 70, 72, 74, 76. As illustrated, the variableimpedance devices 78, 80 are coupled to the balun 70, the variableimpedance devices 82, 84 are coupled to the balun 72, the variableimpedance devices 86, 88 are coupled to the balun 74, and the variableimpedance devices 90, 92 are coupled to the balun 76. In someembodiments, the variable impedance devices 78, 80, 82, 84, 86, 88, 90,92 may be implemented as impedance tuners, impedance gradients, or both.

An impedance gradient, such as the variable impedance device 78, mayoperate as an impedance switch, and provide a first impedance state(e.g., a lower impedance) in a first operating mode and a secondimpedance state (e.g., a higher impedance than the first impedancestate) in a second operating mode. For example, the first impedancestate may approach or appear as a short or closed circuit (e.g.,approaching or approximately equal to zero ohms, such as between 0 and100 ohms, 0.1 and 10 ohms, 0.5 and 2 ohms, and so on), while the secondimpedance state may approach or appear as an open circuit (e.g.,providing an impedance greater than the first impedance state, such asgreater than 10000 ohms, greater than 1000 ohms, greater than 100 ohms,greater than 10 ohms, greater than 5 ohms, and so on). The impedancegradient may be made of any suitable circuit components that enable thefirst and second impedance states, such as, for example, any suitablecombination of inductors and capacitors.

An impedance tuner, such as the variable impedance device 80, mayoperate as a tunable impedance device, and provide multiple impedancestates. For example, the impedance states may include a first impedancestate approaching or appearing as a short or closed circuit (e.g.,approaching or approximately equal to zero ohms, such as between 0 and100 ohms, 0.1 and 10 ohms, 0.5 and 2 ohms, and so on), a secondimpedance state approaching or appearing as an open circuit (e.g.,providing an impedance greater than the first impedance state, such asgreater than 50000 ohms, such as greater than 10000 ohms, greater than1000 ohms, greater than 100 ohms, greater than 10 ohms, greater than 5ohms, and so on), and multiple states providing impedances (e.g.,between 0 and 50000 ohms) in between the first and second impedancestates. An impedance tuner may be made of any suitable circuitcomponents that enable the multiple impedance states, such as, forexample, any suitable combination of inductors and capacitors. It shouldbe understood that these impedance devices are provided as examples, andany suitable device that provides different impedance states and/orvalues, such as an impedance switch or variable impedance device, iscontemplated.

Each variable impedance device (e.g., 78, 82, 86, 90 is paired with acorresponding variable impedance device (e.g., 80, 84, 88, 92). That is,the variable impedance device 78 is paired with the variable impedancedevice 80, the variable impedance device 82 is paired with the variableimpedance device 84, the variable impedance device 86 is paired with thevariable impedance device 88, and the variable impedance device 90 ispaired with the variable impedance device 92. These pairs of variableimpedance devices can be balanced (or unbalanced) to block (or enable) asignal to pass therethrough. Advantageously, blockage of a signal (e.g.,isolation provided by the pairs of variable impedance devices) may beindependent of an impedance mismatch of the one or more antennas 55.That is, the impedance of the one or more antennas 55 may not affect theeffectiveness of blocking a signal resulting from placing a pair ofvariable impedance devices in a balanced state.

The balun 70 may isolate the TX circuit 52 from the RX signal when thecorresponding variable impedance devices 78, 80 are in a balanced statefor a reception frequency (e.g., a frequency supported by the RX circuit54) of the RX signal. That is, the variable impedance devices 78, 80 mayblock the RX signal from passing through to the TX circuit 52 when theimpedances of the variable impedance devices 78, 80 are in a balancedstate (e.g., correlate or approximately match in impedance). At the sametime, the balun 70 may enable the TX signal to pass therethrough fromthe TX circuit 52 to the one or more antennas 55 when the correspondingvariable impedance devices 78, 80 are in an unbalanced state (e.g., notcorrelate or approximately match in impedance) for a transmissionfrequency (e.g., a frequency supported by the TX circuit 52) of the TXsignal.

Additionally, the balun 72 may substantially prevent (e.g., mitigate orreduce an occurrence of) a TX leakage signal from the TX circuit 52 tothe RX circuit 54 by reducing or cancelling the TX leakage signal. Forexample, the balun 70 may generate the TX leakage signal. The balun 72may generate a TX leakage cancellation signal that is equal and oppositeto (e.g., equal in amplitude and opposite in phase) the TX leakagesignal generated by the balun 70. In some embodiments, to generate thecancellation signal, the balun 72 may be configured in an oppositepolarity from the balun 70. Thus, the TX leakage signal generated by thebalun 72 destructively combines with the TX leakage cancellation signalgenerated by the balun 72, effectively cancelling the TX leakage signalgenerated by the balun 70 and substantially preventing the TX leakagesignal generated by the balun 70 from propagating to the baluns 74, 76.

Similarly, the balun 76 may substantially prevent (e.g., mitigate orreduce) an RX leakage signal generated by the balun 74 by generating anRX leakage cancellation signal that is equal and opposite to (e.g.,equal in amplitude and opposite in phase) the RX leakage signalgenerated by the balun 74. In some embodiments, to generate thecancellation signal, the balun 76 may be configured in an oppositepolarity from the balun 74. The RX leakage signal generated by the balun76 destructively combines with the RX leakage cancellation signalgenerated by the balun 74, effectively cancelling the RX leakage signalgenerated by the balun 74 and substantially preventing the RX leakagesignal generated by the balun 74 from propagating to the baluns 70, 72.Thus, the baluns 70, 72, 74, 76 may prevent or mitigate (or reduce anoccurrence of) interference between the TX and RX signals while reducingan occurrence of damage to the TX circuit 52 and the RX circuit 54. Asdiscussed above, the baluns 72, 76 may improve isolation effectivenessof the isolation provided by the baluns 70, 74 of the RX circuit 54 fromthe TX signal and isolation of the TX circuit 52 from the RX signalreceived via the one or more antennas 55.

That is, the balun 70 may isolate the TX circuit 52 from the RX signalwhile the balun 72 may substantially prevent (or mitigate) a leakagesignal (e.g., leakage from the TX signal) from the TX circuit 52 to theRX circuit 54. Similarly, the balun 74 isolates the RX circuit 54 fromthe TX signal while the balun 76 substantially prevents (orsubstantially reduce an occurrence of) an RX leakage signal (e.g.,leakage from the RX signal) from the one or more antennas 55 to the TXcircuit 52 by cancelling the RX leakage signal.

During operation, a combination of the baluns 72, 76 and correspondingvariable impedance devices 82, 84, 90, 92 (e.g., without the baluns 70,74 and corresponding variable impedance devices 78, 80, 86, 88) mayfunction similar to a double-balanced duplexer (e.g., without the baluns70, 74). Similarly, a combination of the baluns 70, 74 and correspondingvariable impedance devices 78, 80, 86, 88 (e.g., without the baluns 72,76 and corresponding variable impedance devices 82, 84, 90, 92) mayfunction similar to a double-balanced duplexer. However, as discussedabove, each combination of the baluns 70, 74 or 72, 76 may not havesufficient bandwidth to support high bandwidth operation due to therelatively large insertion loss caused by the baluns 70, 74 or 72, 76.

In combination, the baluns 70 with 72 and/or 74 with 76 (andcorresponding variable impedance devices) may increase the bandwidth ofthe transceiver circuitry 50 by reducing or mitigating the leakagesignals. That is, the baluns 70, 72 (and corresponding variableimpedance devices) may enable a bandwidth of the TX signal of thetransceiver circuitry 50 to be greater than 10 MHz, such as between 10MHz and 1 gigahertz (GHz) (e.g., 300 MHz). Similarly, the baluns 74, 76may enable a bandwidth of the RX signal of the transceiver circuitry 50to be greater than 10 MHz, such as between 10 MHz and 1 gigahertz (GHz)(e.g., 300 MHz). That is, the baluns 70, 72, 74, 76 may enabletransmission of a TX signal via the one or more antennas within afrequency range of greater than 10 MHz and block a reception signalwithin a frequency range of greater than 10 MHz from passing through tothe TX circuit 52. In some embodiments, the frequency range of thetransmitted TX signal and a blocked RX signal may be greater than 100MHz, greater than about 200 MHz, and the like. Accordingly, the baluns70, 72, 74, 76 improve effectiveness of the isolation of the RX circuit54 from the TX signal transmitted by the TX circuit 52 and isolation ofthe TX circuit 52 from the RX signal received via the one or moreantennas 55. Thus, the transceiver circuitry 50 may support increaseddata transfer speeds, reduce an occurrence of interference between theTX and RX signals, and reduce an occurrence of damage caused to the TXcircuit 52 and the RX circuit 54 due to signal leakage. While thetransceiver circuitry 50 is illustrated in FIG. 5 including baluns 70,72, 74, 76, it should be understood that any suitable isolationcircuitry can be used to isolate the RX circuit 54 from the TX signal(and TX noise signal) transmitted by the TX circuit 52 and isolate theTX circuit 52 from the RX signal (and RX noise signal) received via theone or more antennas 55.

FIG. 6 is a schematic diagram of an example duplexer 100 of thetransceiver circuitry 50 of FIG. 3 having additional variable impedancedevices to enhance isolation, according to an embodiment of the presentdisclosure. The duplexer 100 is similar to the baluns 70, 72, 74, 76 ofthe transceiver circuitry of FIG. 5, with additional variable impedancedevices coupled to each coil of a balun 102. In some embodiments, thetransceiver circuitry 50 of FIG. 5 may be implemented by replacing anyor all of the baluns 70, 72, 74, 76 and corresponding variable impedancedevices 78, 80, 82, 84, 86, 88, 90, 92 with the duplexer 100 andcorresponding variable impedance devices 112, 114, 116, 118 of FIG. 6.As illustrated, the duplexer 100 may be disposed between andcommunicatively coupled to the RX circuit 54 and the one or moreantennas 55. In additional or alternative embodiments, the duplexer 100may be disposed between and communicatively coupled to the TX circuit 52and the one or more antennas 55. The duplexer 100 includes the balun 102and a number of variable impedance devices 112, 114, 116, 118 coupled tothe balun 102. The variable impedance devices 112, 114, 116, 118 may beimplemented as impedance tuners, impedance gradients, LC matchingnetworks, or a combination thereof.

A first side 120 of the balun 102 includes a first set of coils(windings) 104, 108 coupled to the RX circuit 54. A first variableimpedance device 112 and a second variable impedance device 114 arecoupled to opposing ends of the first set of coils 104, 108. The RXcircuit 54 is coupled to a first variable impedance device 112 via afirst coil 104 of the first set of coils and coupled to a secondvariable impedance device 114 via a second coil 108 of the first set ofcoils.

A second side 122 of the balun 102 includes a second set of coils 106,110 coupled to the one or more antennas 55. A third variable impedancedevice 116 and a fourth variable impedance device 118 are coupled toopposing ends of the second set of coils 104, 108. The one or moreantennas 55 is coupled to a third variable impedance device 116 via athird coil 106 of the second set of coils and coupled to a fourthvariable impedance device 118 via a fourth coil 110 of the second set ofcoils.

During operation, the third variable impedance device 116 may have a lowimpedance in the pass band of the RX frequency and a high impedance inthe block band of the RX frequency. The fourth variable impedance device118 may have a high impedance in the pass band and a high impedance inthe block band of the RX frequency. That is, the third variableimpedance device 116 and the fourth variable impedance device are in anunbalanced state in the pass band and in a balanced state in the blockband. The unbalanced state enables pass-through of signals having afrequency in the pass band. Similarly, the balanced state blocks signalshaving a frequency in the block band. The first variable impedancedevice 112 may have a high impedance in the pass band and a highimpedance in the block band, of the RX frequency. The second variableimpedance device 114 may have a low impedance in the pass band and ahigh impedance in the block band. That is, the first variable impedancedevice 112 and the second variable impedance device 114 are in anunbalanced state in the pass band an in a balanced state in the blockband, of the RX frequency.

While the duplexer 100 is illustrated to include the balun 102 disposedbetween the RX circuit 54 and the one or more antennas 55, it should beunderstood that other arrangements are possible. For example, theduplexer 100 may be disposed between the TX circuit 52 and the one ormore antennas 55. That is, the RX circuit 54 in FIG. 6 may be replacedby the TX circuit 52. In that case, the first variable impedance device112 and the third variable impedance device 116 may be open and thesecond variable impedance device 114 and the fourth variable impedancedevice 118 may be closed, at the frequency of the TX signal. That is,the first and third variable impedance devices 112, 116 may have a highimpedance in the pass band of the TX frequency and the second and fourthvariable impedance devices 114, 118 may have a low impedance at the TXfrequency.

The duplexer 100 provides additional isolation between the RX signal andthe TX circuit 52 and between the TX signal and the RX circuit 54 whenboth the first side 120 and the second side 122 of the balun 102 are ina balanced state. Advantageously, the substantial balancing of theimpedances in the transceiver circuitry 50 (e.g., the substantialequivalence of the impedance ratios) provides an improved isolation ofthe RX circuit 54 from the TX signal and improved isolation of the TXcircuit 52 from the RX signal. The improved isolation provided by theduplexer 100 is discussed in more detail with respect to FIG. 7 below.

FIG. 7 is a schematic diagram of an example double balanced duplexer(DBD) 130 implemented with the duplexer 100 of FIG. 6, according to anembodiment of the present disclosure. The DBD 130 includes a firstduplexer 168 and a second duplexer 170. The first duplexer 168 and thesecond duplexer 170 are substantially similar to the duplexer 100discussed with respect to FIG. 6. As illustrated, the first duplexer 168is disposed between the TX circuit 52 and the one or more antennas 55.The second duplexer 170 is disposed between the RX circuit 54 and theone or more antennas 55.

The first duplexer 168 includes a balun 132 having a first set of coils136, 140 and a second set of coils 138, 142. A first variable impedancedevice 154 is coupled to a first coil 136 of the first set of coils anda second variable impedance device 156 is coupled to a second coil 140of the first set of coils. That is, the first variable impedance device154 and the second variable impedance device 156 are coupled to oppositeends of the first set of coils 136, 140. Similarly, a third variableimpedance device 152 is coupled to a third coil 138 of the second set ofcoils and a fourth variable impedance device 158 is coupled to a fourthcoil 142 of the second set of coils. That is, the third variableimpedance device 152 and the fourth variable impedance device 158 arecoupled to opposite ends of the second set of coils 138, 142.

The second duplexer 170 includes a balun 134 having a first set of coils144, 148 and a second set of coils 146, 150. A fifth variable impedancedevice 162 is coupled to a first coil 144 of the first set of coils anda sixth variable impedance device 164 is coupled to a second coil 148 ofthe first set of coils. That is, the fifth variable impedance device 162and the sixth variable impedance device 164 are coupled to opposite endsof the first set of coils 144, 148. Similarly, a seventh variableimpedance device 160 is coupled to a third coil 146 of the second set ofcoils and an eighth variable impedance device 166 is coupled to a fourthcoil 150 of the second set of coils. That is, the seventh variableimpedance device 160 and the eighth variable impedance device 166 arecoupled to opposite ends of the second set of coils 146, 150.

As discussed with respect to the duplexer 100 in FIG. 6, each of theduplexers 168, 170 may operate in a balanced or unbalanced statedepending on the frequency ranges of the TX signal and RX signal. Thatis, the first duplexer 168 may provide isolation of the TX circuit 52from the RX signal in the RX frequency range when the balun 132 is in abalanced state. Similarly, the second duplexer 170 may provide isolationof the RX circuit from the TX signal (e.g., leakage of the TX signal) inthe TX frequency range when the balun 134 is in a balanced state. Insome embodiments, the DBD 130 is tunable by changing an impedance of oneor more of the variable impedance devices 152, 154, 156, 158, 160, 162,164, 166.

The variable impedance devices 154, 156 provide isolation of the TXcircuit from the RX signal and the variable impedance devices 152, 158provide additional isolation of the TX circuit 52 from the RX signal.Similarly, the variable impedance devices 160, 166 provide isolation ofthe RX circuit from the TX signal and the variable impedance devices162, 164 provide additional isolation of the RX circuit 54 from the TXsignal. Thus, the first duplexer 168 (e.g., the balun 132 and thevariable impedance devices 152, 154, 156, 158) improves isolationbetween the RX signal and the TX circuit 52 and the second duplexer 170(e.g., the balun 134 and the variable impedance devices 160, 162, 164,166) improves isolation between the TX signal (and TX signal leakage)and the RX circuit 54. Further, the DBD 130 provides an increasesbandwidth available for the TX signal to greater than 10 MHz, such asabout 100 MHz, compared to a conventional DBD with a single impedancedevice on each side of the baluns.

FIG. 8 is a schematic diagram of an example quadplexer module 180 of thetransceiver circuitry 50 of the electronic device of FIG. 1, accordingto an embodiment of the present disclosure. The quadplexer module 180may split one input signal into four output signals. In particular, thequadplexer module 180 may route an RX signal received via the one ormore antennas 55 to multiple RX circuits 54. Similarly, the quadplexermodule 180 may route TX signals from multiple TX circuits 52 to the oneor more antennas 55. As illustrated, the quadplexer module 180 includesa quadplexer 186 coupled to a first DBD 182 and a second DBD 184. Thefirst DBD 182 and the second DBD 184 may be substantially similar to theDBD 130 discussed with respect to FIG. 7. That is, each of the first DBD182 and the second DBD 184 include the first duplexer 168 and the secondduplexer 170 discussed with respect to FIG. 7. As illustrated, the firstDBD 182 and the second DBD 184 are coupled to a common set of (e.g., oneor more) antennas 55. In some embodiments, each of the first DBD 182 andthe second DBD 184 may be coupled to separate antennas among theantennas 55.

As discussed above, the first DBD 182 and the second DBD 184 may betunable by adjusting an impedance of the variable impedance devices 152,154, 156, 158, 160, 162, 164, 166. In some embodiments, in addition toor in the alternative of the first DBD 182 and the second DBD 184 beingtunable, the quadplexer module 180 may include additional DBDs to enablefurther increase bandwidth available for the TX signal and the RXsignal.

In operation, the quadplexer 186 may receive RX signals from the one ormore antennas 55 in different frequency bands to be sent to respectiveRX circuits 54. The quadplexer 186 may also receive TX signals indifferent frequency bands from respective TX circuits 52 and route theTX signals to the one or more antennas 55. In some embodiments, each ofthe frequency bands of the various RX signals and TX signals may each bedifferent. In additional or alternative embodiments, at least some ofthe frequency bands of the various RX signals and TX signals mayoverlap. As discussed below with respect to FIG. 9, the quadplexer 186may function as a tunable filter to enable transmission and/or receiptof signals having various frequencies or frequency bands. Similarly, thequadplexer may be tunable to block transmission and/or receipt ofsignals having various frequencies or frequency bands. Thus, thequadplexer 186 enables improved isolation within the transceivercircuitry 50 discussed with respect to FIG. 3.

FIG. 9 is a schematic diagram illustrating example components of theexample quadplexer module 180 of FIG. 8, according to an embodiment ofthe present disclosure. As illustrated, the quadplexer 186 includesfirst isolation circuitry 188 coupled to and disposed between the firstDBD 182 and the one or more antennas 55. The quadplexer 186 alsoincludes second isolation circuitry 190 coupled to and disposed betweenthe second DBD 184 and the one or more antennas 55.

The first isolation circuitry 188 includes a first balun 200 coupled inparallel to a second balun 202. The first balun 200 includes a first setof coils 208, 212 and a second set of coils 210, 214. A first variableimpedance device 242 is coupled to a first coil 208 of the first set ofcoils and a second variable impedance device 244 is coupled to a secondcoil 212 of the first set of coils. That is, the first variableimpedance device 242 and the second variable impedance device 244 arecoupled to opposite ends of the first set of coils 208, 210. Similarly,a third variable impedance device 240 is coupled to a third coil 210 ofthe second set of coils and a fourth variable impedance device 246 iscoupled to a fourth coil 214 of the second set of coils. That is, thethird variable impedance device 240 and the fourth variable impedancedevice 246 are coupled to opposite ends of the second set of coils 210,214.

The first balun 200, in conjunction with the third variable impedancedevice 240 and the fourth variable impedance device 246, may provideisolation between the first DBD 182 and signals from and to the secondDBD 184. The first balun 200, in conjunction with the first variableimpedance device 242 and the second variable impedance device 244, mayprovide additional isolation between the first DBD 182 and signals fromand to the second DBD 184, essentially implementing the duplexer 100 ofFIG. 10.

The second balun 202 includes a third set of coils 216, 220 and a fourthset of coils 218, 222. A fifth variable impedance device 248 is coupledto a first coil 216 of the third set of coils and a sixth variableimpedance device 254 is coupled to a second coil 220 of the third set ofcoils. That is, the fifth variable impedance device 248 and the sixthvariable impedance device 254 are coupled to opposite ends of the thirdset of coils 216, 220. Similarly, a seventh variable impedance device250 is coupled to a third coil 218 of the fourth set of coils and aneighth variable impedance device 252 is coupled to a fourth coil 222 ofthe fourth set of coils. That is, the seventh variable impedance device250 and the eighth variable impedance device 252 are coupled to oppositeends of the fourth set of coils 218, 222.

The second balun 202 may mitigate (or substantially prevent or reduce anoccurrence of) a leakage signal from the first DBD 182 to the secondisolation circuitry 190. Moreover, the second balun 202, in conjunctionwith the fifth variable impedance device 248 and the sixth variableimpedance device 254, may provide isolation between the first DBD 182and signals from and to the second DBD 184. The second balun 202, inconjunction with the seventh variable impedance device 250 and theeighth variable impedance device 252, may provide additional isolationbetween the first DBD 182 and signals from and to the second DBD 184.

The second isolation circuitry 190 includes a third balun 204 coupled inparallel to a fourth balun 206. The third balun 204 includes a first setof coils 224, 228 and a second set of coils 226, 230. A ninth variableimpedance device 258 is coupled to a first coil 224 of the first set ofcoils and a tenth variable impedance device 260 is coupled to a secondcoil 228 of the first set of coils. That is, the ninth variableimpedance device 258 and the tenth variable impedance device 260 arecoupled to opposite ends of the first set of coils 224, 228. Similarly,an eleventh variable impedance device 256 is coupled to a third coil 226of the second set of coils and a twelfth variable impedance device 262is coupled to a fourth coil 230 of the second set of coils. That is, theeleventh variable impedance device 256 and the twelfth variableimpedance device 262 are coupled to opposite ends of the second set ofcoils 226, 230.

The third balun 204, in conjunction with the eleventh variable impedancedevice 256 and the twelfth variable impedance device 262, may provideisolation between the second DBD 184 and signals from and to the firstDBD 182. The third balun 204, in conjunction with the ninth variableimpedance device 258 and the tenth variable impedance device 260, mayprovide additional isolation between the second DBD 184 and signals fromand to the first DBD 182.

The fourth balun 206 includes a third set of coils 232, 236 and a fourthset of coils 234, 238. A thirteenth variable impedance device 264 iscoupled to a first coil 232 of the third set of coils and a fourteenthvariable impedance device 272 is coupled to a second coil 236 of thethird set of coils. That is, the thirteenth variable impedance device264 and the fourteenth variable impedance device 272 are coupled toopposite ends of the third set of coils 232, 236. Similarly, a fifteenthvariable impedance device 268 is coupled to a third coil 234 of thefourth set of coils and a sixteenth variable impedance device 270 iscoupled to a fourth coil 238 of the fourth set of coils. That is, thefifteenth variable impedance device 268 and the sixteenth variableimpedance device 270 are coupled to opposite ends of the fourth set ofcoils 234, 238.

The fourth balun 206 may mitigate (or substantially prevent or reduce anoccurrence of) a leakage signal from the second DBD 184 to the firstisolation circuitry 188. Moreover, the fourth balun 206, in conjunctionwith the thirteenth variable impedance device 264 and the fourteenthvariable impedance device 272 may provide isolation between the secondDBD 184 and signals from and to the first DBD 182. The fifteenthvariable impedance device 268 and the sixteenth variable impedancedevice 270 (in conjunction with the fourth balun 206) may provideadditional isolation between the second DBD 184 and signals from and tothe first DBD 182.

Similar to the variable impedance devices 152, 154, 156, 158, 160, 162,164, 166 discussed with respect to FIG. 7, the impedances of thevariable impedance devices 240, 242, 244, 246, 248, 250, 252, 254, 256,258, 260, 262, 264, 266, 268, 270, 272 can be tuned such that each ofthe baluns 200, 202, 204, 206 are in a balanced state to improveisolation of the TX signal and TX signal leakage and the RX circuits 54and isolation of the RX signal and the TX circuits 52. That is, thequadplexer 186 is similar to the isolation circuitry 58 discussed withrespect to FIG. 5, with additional variable impedance devices coupled tothe baluns 200, 202, 204, 206. That is, the quadplexer 186 is acombination of the isolation circuitry 58 of FIG. 5 and the duplexer 100discussed with respect to FIG. 6. Thus, the quadplexer 186 providesimproved isolation between the DBDs 182, 184 and increases bandwidth forwireless communications available to the electronic device 10.

The specific embodiments described above have been shown by way ofexample, and it should be understood that these embodiments may besusceptible to various modifications and alternative forms. It should befurther understood that the claims are not intended to be limited to theparticular forms disclosed, but rather to cover all modifications,equivalents, and alternatives falling within the spirit and scope ofthis disclosure.

The techniques presented and claimed herein are referenced and appliedto material objects and concrete examples of a practical nature thatdemonstrably improve the present technical field and, as such, are notabstract, intangible or purely theoretical. Further, if any claimsappended to the end of this specification contain one or more elementsdesignated as “means for [perform]ing [a function] . . . ” or “step for[perform]ing [a function] . . . ,” it is intended that such elements areto be interpreted under 35 U.S.C. 112(f). However, for any claimscontaining elements designated in any other manner, it is intended thatsuch elements are not to be interpreted under 35 U.S.C. 112(f).

1. An electronic device comprising: one or more antennas; transmitcircuitry configured to send a transmission signal to the one or moreantennas; receive circuitry configured to receive a reception signalfrom the one or more antennas; and isolation circuitry configured toisolate the receive circuit from the transmission signal, the isolationcircuitry comprising a first balun coupled between the one or moreantennas and the receive circuitry, a first variable impedance devicecoupled to the first balun, a second variable impedance device coupledto the first balun, a second balun coupled to the one or more antennasand the transmit circuitry, a third variable impedance device coupled tothe second balun, and a fourth variable impedance device coupled to thesecond balun.
 2. The electronic device of claim 1, wherein the isolationcircuitry is configured to isolate the receive circuitry from thetransmission signal when the first variable impedance device and thesecond variable impedance device are in a balanced state.
 3. Theelectronic device of claim 1, wherein the first variable impedancedevice and the second variable impedance device are coupled to opposingends of a first set of coils of the first balun, and wherein the thirdvariable impedance device and the fourth variable impedance device arecoupled to opposing ends of a second set of coils of the first balun. 4.The electronic device of claim 3, wherein the receive circuitry iscoupled to the first balun between the first set of coils, and whereinthe transmit circuitry is coupled to the second balun between the secondset of coils.
 5. The electronic device of claim 1, comprising a fifthvariable impedance device coupled to the first balun, a sixth variableimpedance device coupled to the first balun, a seventh variableimpedance device coupled to the second balun, and an eighth variableimpedance device coupled to the second balun.
 6. The electronic deviceof claim 5, wherein the first balun is configured to isolate the receivecircuitry from the transmission signal when the fifth variable impedancedevice and the sixth variable impedance device are in a balanced stateat a frequency of the transmission signal.
 7. The electronic device ofclaim 1, wherein the isolation circuitry comprises a third balun coupledbetween one or more antennas and the receive circuitry configured toprevent a leakage current at a frequency of the transmission signal fromentering the receive circuitry, and a fourth balun coupled to the one ormore antennas and the transmit circuitry configured to isolate thetransmit circuitry from the reception signal.
 8. The electronic deviceof claim 1, wherein the first balun is disposed in parallel with thesecond balun.
 9. Radio frequency transceiver circuitry comprising:transmit circuitry communicatively coupled to one or more antennas, thetransmit circuitry configured to send a transmission signal to the oneor more antennas; receive circuitry communicatively coupled to the oneor more antennas, the receive circuitry configured to receive areception signal from the one or more antennas; and isolation circuitrycomprising a first balun transformer coupled between the one or moreantennas and receive circuitry, a first set of variable impedancedevices coupled to the first balun transformer, the first set ofvariable impedance devices configured to isolate the receive circuitryfrom the transmission signal when the first set of variable impedancedevices are in a balanced state, a second balun transformer coupledbetween the one or more antennas and the second balun transformer, and asecond set of variable impedance devices coupled to the second baluntransformer, the second set of variable impedance devices configured toisolate the transmit circuitry from the reception signal when the secondset of variable impedance devices are in the balanced state.
 10. Theradio frequency transceiver circuitry of claim 9, wherein the firstbalun transformer comprises a first set of coils, the first set ofvariable impedance devices comprises first and second variable impedancedevices coupled to opposing ends of the first set of coils, the secondbalun transformer comprises a second set of coils, and the second set ofvariable impedance devices comprises third and fourth variable impedancedevices coupled to opposing ends of the second set of coils.
 11. Theradio frequency transceiver circuitry of claim 9, wherein the first andsecond variable impedance devices are configured to isolate the receivecircuitry from the transmission signal when in a balanced state andenable the receive circuitry to receive the reception signal from theone or more antennas when in an unbalanced state.
 12. The radiofrequency transceiver circuitry of claim 9, wherein the reception signalis within a first frequency range, and the transmission signal is withina second frequency range.
 13. The radio frequency transceiver circuitryof claim 12, wherein the first frequency range is greater than 100megahertz (MHz) and the second frequency range is between 10 MHz and 100MHz.
 14. An electronic device comprising: one or more antennas; firstisolation circuitry coupled to the one or more antennas; a firstduplexer coupled to the first isolation circuitry; second isolationcircuitry coupled to the one or more antennas; and a second duplexercoupled to the second isolation circuitry.
 15. The electronic device ofclaim 14, wherein the first isolation circuitry comprises a first baluncoupled to the one or more antennas and the first duplexer, a first setof variable impedance devices coupled to the first balun, a second baluncoupled to the one or more antennas and the first duplexer, and a secondset of variable impedance devices coupled to the second balun.
 16. Theelectronic device of claim 15, wherein the first balun is coupled inparallel with the second balun.
 17. The electronic device of claim 14,wherein the second isolation circuitry comprises a third balun coupledto the one or more antennas and the second duplexer, a third set ofvariable impedance devices coupled to the third balun, a fourth baluncoupled to the one or more antennas and the second duplexer in parallelwith the third balun, and a fourth set of variable impedance devicescoupled to the fourth balun.
 18. The electronic device of claim 17, thefirst duplexer comprising a first plurality of variable impedancedevices coupled to opposing ends of a first set of coils of the thirdbalun, and a second plurality of variable impedance devices coupled toopposing ends of a second set of coils of the fourth balun.
 19. Theelectronic device of claim 14, wherein the first duplexer comprises athird balun coupled to the one or more antennas and receive circuitry,the receive circuitry configured to receive a reception signal from theone or more antennas, and a fourth balun coupled to the one or moreantennas and transmit circuitry, the transmit circuitry configured tosend a transmission signal to the one or more antennas.
 20. Theelectronic device of claim 19, wherein the second duplexer comprises afifth balun coupled to the one or more antennas and the receivecircuitry, a first plurality of variable impedance devices coupled tothe fifth balun, a sixth balun coupled to the one or more antennas andthe transmit circuitry, and a second plurality of variable impedancedevices coupled to the sixth balun.